Particles which have a weight average particle size of 1.0-30.0 .mu.m and a particle size distribution variation coefficient of less than 20% are widely used for various applications such as a carrier of a diagnostic agent used for clinical test, a spacer for a liquid crystal display, powder ink, etc. However, particles suitable for such applications, which satisfy the requirement of both heat resistance and solvent resistance, have not been developed yet.
For instance, Makromol. Chem. 1979, 180-737, discloses vinyl polymer gel particles which are crosslinked with divinylbenzene, by way of seed polymerization. However, the particles thus obtained are not suitable for the above mentioned applications, because they neither satisfy the requirements of heat resistance and solvent resistance nor have poor mechanical strength.
Japanese Kokai Publication Sho 4(1992)-211415 discloses vinyl polymer gel particles which are obtained by interfacial polymerization. The particles obtained thereby may have superior heat resistance and solvent resistance by choosing appropriate monomers, but have very broad particle size distribution and it is very difficult to apply them to the above mentioned application.